Chinese is a use-it-or-lose-it language, at least as far as the writing goes. I used to be able to write a fair amount, and read even more, but now that's pretty well gone. Even the Chinese folks I know who have been in the U.S. for a while notice that they've forgotten a lot. Since each word has to be memorized individually, it's easy to lose the ones you don't use.
The spoken language is a little easier to hang on to. As long as I don't think too hard about it, I can carry on a normal conversation still.
Ni hao, Zhongguo ren!